This invention relates to a scraper arrangement for a conveyor belt.
Conveyor belts which are used for transporting fine material which may be damp or wet can pose particular problems. For example fine ash which is produced in a power station can, especially as a result of ash collection techniques, become damp or wet and when conveyed on a belt can adhere to the belt and build up substantial bulky deposits of ash which may be difficult to remove.
A conveyor belt is scraped clean by means of a primary or secondary scraper, or both. A primary scraper is used to effect an initial scraping action while a secondary scraper is used with a finer scraping action to remove remaining residual material.
Primary and secondary scrapers have been strengthened so that they can remove packed bulky material of the kind referred to. Although this approach may hold certain benefits it is found that the strengthened scrapers are then too stiff and are not able to exhibit a normal scraping action.
A need therefore exists for some means which is capable of removing sticky packed material of the kind referred to but without interfering with the designed or intended scraping action of a secondary scraper or a primary scraper if one is used.
The invention provides, in the first instance; a scraper assembly cartridge which includes a base, a bracing member which extends from the base, and a plurality of scraping elements which are fixed to the bracing member.
Preferably the base is channel shaped with opposing spaced lips.
Preferably the bracing member is rigid and the scraping elements are rigidly fixed in line with one another to the bracing member.
The invention also provides a scraper arrangement for a conveyor belt which passes around a head pulley, the scraper arrangement including at least one scraping element with a scraping edge, the scraping element being mounted opposing the belt as it passes around the head pulley and the scraping edge being spaced from the conveyor belt.
The scraping edge may be spaced from an outer surface of the conveyor belt by any appropriate distance and for example may be spaced by a maximum of 6 mm and, preferably, by a distance of approximately 4 mm, depending on the degree of roundness of the conveyor pulley and variations, in the thickness of the conveyor belt along its length.
The scraper arrangement may include at least one support, and at least one arm which is mounted for limited pivotal movement about an axis relatively to the support, the said at least one scraping element being fixed directly or indirectly to the arm.
The scraping edge may be positioned so that it is on or below a line which extends radially from the centre of the head pulley to the said axis. This arrangement resists material passing between the scraping edge and the pulley surface yet allows the scraper assembly to pivot about the axis should there be a permanent or significant obstruction on the conveyor belt.
The scraping element may be mounted to a member which extends transversely to the direction in which the belt moves and which is engaged with two of the said arms located respectively on opposing sides of the belt.
The arms and the member may be pivotal in unison about the said axis.
Each scraping element may be fixed to a base which is engageable in any appropriate manner with the transverse member. Preferably the base is engageable with a sliding action with the member.
The base may be in the shape of a channel and include lips which enable the base to be engaged with a sliding action with the member but which prevent the base from being directly disengaged from the member by moving the base in a direction which is transverse to the direction in which the member extends.
A plurality of scraping elements may be positioned side by side and in line with one another on the base.
Means may be provided for adjusting the position of the axis relatively to the belt. Such means may be adjusted for moving the axis towards or away from the belt according to requirement.
According to a different aspect of the invention there is provided a scraper arrangement for a conveyor belt which passes around a head pulley, the scraper arrangement including at least one scraping element which is mounted for limited pivotal movement about an axis and which has a scraping edge which is positioned below a line which extends radially from a centre of the head pulley to the said axis.